Communication system



0 d. 12, 1937.. I s, EMM N 2,095,336

' COMMUNICATION SYSTEM Filed May 18, 1935 Ana/flew 41m INVENTOR v. M

Ai' oRNEY Patented Oct. 12, 1937 U I I UNl TED sTATEs PATENT ofFicE COMMUNICATION SYSTEM Walter 8. Lemon, New-York, N.

Y., assignor to ApplicationMay 18, 1935, Serial No. 22,200

'3Claims.

' This invention relates to communication systems and more particularly to printing telegraph systems and is suitably adaptable to both radio and wire network transmission. 5 The present invention will be explained in con-' junction with a single impulse synchronous transmission system, in which the different characters to be transmitted and received are represented by single impulse signals which are deflnitely allocated'during particular timed intervals. Inasmuch as the wave shapes of the signals may be all the same length and amplitude with respect to time, they can be similarly dealt with in transmission.

This invention consists of a method and means for the transmission and reception of printing telegraph signals, the system being characterized by the transformation of the wave shape of the signal during the progress of its transmission or reception or both.

An object of this invention is to provide abbreviating means for controlling the time duration of the character pulse independently of the time duration of the impulse impressed on the input of the receiving system.

Another object of the present invention is to provide means for accomplishing the abbreviation of the signal impulses mechanically.

Various other objects and advantages of the 80 invention will be obvious from the following particular .description of one form of mechanism.

embodying the invention or from an inspection of the accompanying drawing; and the invention also constitutes certain. new and useful features 85 of construction and combination of parts hereinafter set forth and claimed.

In the drawing:

Fig. 1 shows a partial sectional view of the preferred form of signal source or transmitter.

Fig. 2 shows diagrammatically the circuits which may be used to embody the present invention.

It has been found that in synchronous systems of the type to be described, namely, the single impulse system, the margins of operation at higher rates of transmission become quite limited;-

For such rates of transmission, it is necessary to maintain exact synchronism between the transmitting and receiving distributors, and in addition thereto, to transmit and receive the charactersignals by extremely short impulses, so as to be positioned or allocated properly on the distributor segments. However, itis well understood by those acquainted in the art, that transmission'oi' signals either by radio or line networks under such critical conditions set forth numerous disadvantages, and prevent the higher rates of transmission of character signals without utilizlug complicated an?! elaborate correcting systems, which for commercial application-and operation-would be impractical; v f

It has been suggested to utilize a longer impulse i'or transmission purposes, and which is necessary for radio transmission due to distortion and mutilation of the signal wave shapes, and upon its reception at the receiver, to suppress or abbreviate the signal so as to impress but a part of it upon the respective distributor segments. A A system of this type is disclosed in a copending application Ser. No. 730,906, filed June 16, 15

1934, the principle of which, applied to the above mentioned system rendering faster possible rates of transmission than heretofore- The system just mentioned in the said application is based on an electrical abbreviating system utilizing" thermionic devices adapted to trigger controlling electrostatic devices.

The present invention contemplates a similar treatment of the signal wave shapes, however, in contradistinction to the electrical abbreviator provides for a simple and eflicient mechanical abbreviator, the disclosure of which will be set forth presently.

It has been mentioned that the particular embodiment of this invention is in conjunction with a particular type 'of printing telegraph system, however, its application is not limited to the preferred form of illustration, for it will be understood, as the description progresses, that the invention is obviously applicable to other types of selecting or control systems in which signal overlap on distributor or commutator segments or the like is likely to occur.

'It'was mentioned hereinbefore that the particular type of communication system explained in conjunction with'the present invention is a printing telegraph system operable by a line or radio network and involves the shifting of the character impulse along the axis of a timed scale, the position of the impulse thereon determining the character to be selected, and is of the type disclosed in U. S. Patent N 1,927,077, dated September 19, 1933.

Referring now to Fig. l, a printing telegraph translating unit is shown, one well known form of which may be the Electromatic typewriter disclosed in the copending application Serial No. 676,654, filed June 20, 1933 and hence requires only the following brief description.

In the embodiment illustrated in the drawing,

- well known means are provided for actuating the type bars (not shown) by power operated devices comprising a power driven roller ID.

A cam l l is pivoted on one arm of a bell crank lever l2 pivoted in the frame, the other arm of which is operatively connected with one arm of a bell crank lever l3 by means of link M. The other arm of lever I3 is connected to the type bars (not shown) in a well known manner and fully disclosed in the aforesaid application.

The lever I2 is actuated by the cam Ii when the latter engages the driven roller ill to be operated thereby. The engagement of the cam H with the power roller is controlled by means of the key lever I! in a manner which will now be described.

The cam H is resiliently engaged by a spring-' pressed arm 20 which tends to turn it' into engagement with the power driven roller or stop 2| on a lever 22 pivoted on the bell crank l2 and normally arranged in the path of a lug on the cam. When the lever 22 swings to move its stop out of the path of the lug, the arm 20 swings the cam into engagement with the power roller to be actuated thereby to swing the bell crank l2 to actuate its connected mechanism.

The lever 22 has an arm 24 which is provided with an ofiset projection 25 at its end which projects laterally through an opening in the bell crank l2 and engages the bifurcated lower end 26 of an arm 21 of a key lever l1 pivoted on the common rod 28.

It is obvious then that depression of a key lever l1 releases, the revolubly mounted cam II to engage and be actuated by power roller H] in turn operating bell crank l2 and its attached links to cause the associated mechanism, such as the key bars and other operating mechanisms, to be operated.

Attached to the key lever I1 is a connecting link I9 extending to a solenoid l8 disposed beneath the keyboard, so that upon energization of the said solenoid the connected key lever is depressed to operate the connected mechanism in the same manner as just explained.

In addition to actuating the several type bars and connected mechanisms, the revolubly mount-' ed cams are adapted to make and break circuits which may be employed in the transmitting units, the purpose of which will be understood as the description progresses. Upon release of the cam H the ensuing operation thereof causes the contact spring blade 30 by virtue of its attached cam follower roller 3| adapted to engage the cam during its partial revolution, to be urged away from the power roller H! to open the contacts 32 and close the contacts 33. Since the cam turns exactly one half of a revolution before being arrested, the spring blade 30 returns to its normal position as, shown in the drawing by virtue 01 its own resiliency, thereby restoring the contacts to their normal position, that is, contacts 32 closed and contacts 33 open.

It will be understood that the usual number of key bars and power devices with their associated mechanisms are provided, but only one of them is shown for the sake of clearness.

Referring now to Fig. 2, A represents a printing telegraph unit which may be of the type described or any well known type having a' series of character pivoted key bars l1 and adapted to initiate a character impulse when one of the character keys is depressed.

The transmitting contacts may be positioned as explained hereinb'efore so as to open one set 01 contacts and close another by the operating cams II or the contacts may be positioned directly in contact with the keyboard I! and operated thereby, as shown in the figure.

A separate contact 32a is associated with each individual key bar I! and connected to segments 35 of the distributor 36, a portion of the development of which is shown, and further disclosure thereof is deemed unnecessary since their use is well known in the art. Rotary arm 31 driven by any suitable means, such as a motor, is adapted to engage the segments in rather rapid succession to cause the transmission of.the character impulses. One method of setting up the character signals is by the use of condensers and as shown an individual condenser 38 is associated with each key bar H, the said condensers associated with the key bars are connected by a common conductor 39 to the negative side of battery 40. It is to be noted that all the contacts 32a, that is, the normally closed contacts, are associated with separate conducting segments 35 o! the distributor 36.

Disposed beneath or associated. with the key bars I! and normally open are the contacts 33a connected to one side of the condensers 38. These are provided so that when a character key is depressed the condenser 38 normally charged will be discharged by shorting the condenser through contact 33a to ground.

Supposing the key bar corresponding to character A is depressed to discharge its corresponding condenser, upon return of the key bar the contact 32a would be closed to connect the circuit from the negative side of battery 40 through condenser 38 and the closed contact 32a to its corresponding segment 35-4, so that when the rotary arm 31 with its conducting brush 42 engages contact I, a circuit is completed through its other brush 43, solid and common conducting distributor ring 44, conductor 45 and the connected parallel circuit consisting of resistors 46 and the primary winding of transformer 41, to the positive terminal of battery 40. Therefore, it is seen that upon completion of this circuit just described, by the rotating arm 31 engaging the segment 35-l of the distributor the corresponding condenser conditioned upon depression of the A character key by being discharged is now charged through the parallel circuit arrangements 46 and 41 to energize the secondary winding of transformer 41 and its connected circuit which may be a wire or radio transmission network, utilizing transmitting equipment well known in the art, and therefore deemed not necessary to describe in further detail.

It was mentioned that the condensers 38 were assumed to be normally charged, therefore, in order to insure correct operation of the transmitting system upon starting, the normally closed switch 49 included in the input circuit of the signal transmitter is opened, until the individual condensers, which may have been discharged, are charged by having all the distributor segments 35 engaged successively by the rotary arm 31in a manner just described, and in this manner prevent erroneous operation of the receiving system which will now be explained. 4 g

The broad principle of operation of single impulse systems of the type referred to, which is obvious, depends upon the synchronous operation of the distributing or rotary units associated with the respective transmitting and receiving units. Such synchronizing units are old and well known to those skilled in the art, and therefore a detailed description-of this unit is not necessary.- It is suflicient to mention that one type of 'synchronizing unit is such utilizing periodic synchronizing impulses, as, for example, a synchronizing impulse for each revolution of the transmitting rotary distributor, and usually are arranged so that if the rotary distributor atthe receiver lags as compared to the rotation of the transmitting distributor, the receiving rotary brush, by virtue of such lagging, engages a contact segment to'ener gize electro-responsive devices by the transmitted synchronizing impulse to cause the rotary arm at i the receiver to be advanced to such an extent during its rotation so as to traverse the distributor segments in step with the transmitting distributor. If the receiving rotary arm is leading the transmitting arm, engagement ofanother contact segment causes the electro-responsive devices to retard the rotation of the rotary arm until syncronous operation is attained. For a complete description of a synchronizing unit of the type just mentioned, reference may be made to the copending application Serial No. 684,362, filed August 9, 1933 and which plication.

A receiving distributor 5| similar to the trans mitting distributor 35 has disposed thereon the same number of segments 52 which are engaged in succession by brush 53 attached to rotary arm 54 driven by a suitable motor' or device (not shown) so that the arms 5i and-31 are rotated synchronously.

The aperiodically timed character signals are received in the well known manner by a receiver, generally designated, which in turn is associated with a standard and well known type of amplifier 55 consisting of a plurality of thermionic tubes of which two are shown and designated 56 and 51 arranged in cascade and coupled by transformers in the usual manner.

The output of amplifier 58 is connected byone lead to the common conducting ring 59 of distributor 5| constantly engaged by brush 50 also attached to rotary arm 54. The individual segments 52-1, 2, 3, etc. are connected by individual conductors 5| to-one terminal of solenoids is, which as described hereinbefore are linked to a corresponding character key bar i1.

The other terminals are all connected to acommon conductor 62 which forms a return circuit for the output'of the said amplifier.

An auxiliary timing distributor 83 is employed having disposed thereon a plurality of conducting 'is connected to the cathode of tube 51. Segments 64 are adapted to be engaged in succession by a brush 56 attached to rotary arm 61, said arms 61 and 54 may be arranged on a common driven shaft so as to be operated in unison. Conducting brush 68 constantly engages the common solid segment 59 which in turn is connected to the one terminal of the transformer winding, the other end of which is connected to the'grid of tube 51, completing the grid circuit whenever the brush 66 engages one of the segments 64.

The segments 64 are so arranged to be engaged by the brush 66 when the distributor brush 53 engages the central section of the segments 52. So that upon reception of, a character pulse, corresponding to the character A, for example, the distributor arms 54 and 61 will be positioned as can be embodied in this apdescribed hereinbefore so that brush engages segment 52-1 and brush, 55 engages the segmentv 54-i when brush "engages the central section of segment 52-|.

The character signal is received in the well known manner at the receiving station to energize the amplifier 55. However, it is seen that until the grid circuit of tube 51 is completed by the auxiliary distributor the solenoid i8 is not energized by the impulse.

It was mentioned that the segments 54 are shorter than'segments 52 and, it is obvious, that the grid circuit of tube 51 is broken or opened by the auxiliary distributor 63 before the brush 55 is disengaged with the corresponding segment. Therefore, it is possible by controlling the timing operation of the controlgrid of tube 51, the signal pulse may be allocated on the receiving distributor segments 52 at any predetermined section thereof. In addition thereto, by virtue of the short segments 54, overlap is prevented on the distributor segments 52 due to theabbreviated pulse, and in this manner permit a slightly greater drift or synchronizing margin and tolerance.

In order to operate the described system at greater rates of speed an abbreviator method of the type disclosed is highly desirable because the to engage and be actuthe said character accordingly.

In such cases when the abbreviated pulses are not long enough to energize the solenoid l8 directly, a condenser 10 can be bridged across the solenoid l8 to prolong the pulse charge in accordance with the characteristics of the said circuit.

While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a single modification, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention therefore to. be limited only as indicated by the scope of the following claims.

,What is claimed is as follows:

1. In a communication system, a sender and a receiver, each having a circuit control device, the operation of each of said devices being in timed relation with that of the other, a signal key at the sender, a transmission circuit, means whereby signal impulses corresponding to'operations of said signal key are transmitted to said transmission circuit at instants of time governed by the operation of said circuit control device of the sender, said receiver having recording means governed by the circuit controlling device of the receiver, thermionic discharge means associated with said receiver operated by said impulses to be discharged to operate the said recording means, and a. mechanical interrupter operated in synchronism with said circuit control device at the receiver to initiate and terminate the discharge of said thermionic means.

2. In a communication system, means to transmit character impulses including rotary means to initiate differentially timed impulses reprebar l1 to release the senting different characters, and means cooperating therewith to select the-time to initiate the difier ntially timed impulses corresponding to the particular characters to be transmitted, recording means, means 0 receive the said character impulses including rotary means operating in synchronism with the first mentioned rotary means to .govem the time of operation of the recording means, thermionic discharge means associated 10 with the said receiving means operated by the said impulses to be discharged to operate the recording means, and a mechanical interrupter operating in timed relation with the rotary means at the receiver to initiate and terminate the dis- 15 charge of the said thermionic means.

3. In a communication system, in combination, a sending rotary distributor including a series of control segments, a series or printer actuating members each associated with one of thecontrol segments and adapted to transmit printing impulses, means to receive said impulses including a receiving rotary distributor operating in substantial synchronism with the sending distributor; said distributor having disposed thereupon a series of control segments, a series of recording operating elements each associated with one of the last mentioned control segments, the operation of which is governed by the receiving distributor, thermionic discharge means having grid and plate circuits operated by the printing pulses impressed on the grid circuit to. be discharged to operate the said recording elements included in' WALTER S'. LEMIHON. 

